Canine monocytic ehrlichiosis (CME) is an infectious disease caused by Ehrlichia canis, a globally recognized obligate intracellular bacterium. In addition to dogs, other animals, including humans, may be affected. Despite its epidemiological importance and impact on public health, there is currently no commercial vaccine against E. canis. This study aimed to present relevant aspects of the challenges and advances encountered in the development of vaccines for CME and highlight perspectives for future investigations. High genetic variability, along with the various evasion mechanisms employed by E. canis, has hindered the identification of an antigen that targets Th1 cells and is immunogenic to most E. canis isolates, considering their genotypic and phenotypic characteristics. The vaccine must predominantly confer cellular and humoral immunity to achieve robust immune responses. Early production efforts have been challenging due to low immunogenicity, difficulties in establishing long-term protection, and limitations of the techniques used. However, with the refinement of bioinformatic tools, research in this area will be facilitated, thereby accelerating the development of effective vaccines for CME. According to these authors, this vaccine should consist of multiple epitopes.

The risk of zoonotic parasitic infections is closely linked to direct and indirect interactions between animals and humans. The mutual coexistence of species in public spaces predisposes individuals to gastrointestinal parasitosis owing to various social and hygienic-sanitary factors. This study aimed to assess the risk of environmental contamination by gastrointestinal parasites in fecal samples collected from parks and public squares in 18 municipalities located in a microregion of the central plateau of Brazil, correlating the collection with the population size of each municipality. We collected 536 soil fecal samples from 117 randomly selected public areas across a 56,111.874 km² region. Eggs, cysts, and oocysts were detected using the Willis flotation technique and the Hoffman’s spontaneous sedimentation method. The Hoffman’s analysis revealed that 70.3% of the fecal samples were infected across 91.5% of the sampled areas. Identified parasites included the members of the family Ancylostomatidae (56.5%), Toxocara spp. (6.2%), Trichuris spp. (1.7%), Strongyloides spp. (0.2%), Dipylidium caninum (25.8%), Spirometra spp. (0.4%), Taeniidae (0.2%), Platynosomum fastosum (0.6%), Trematoda (0.2%), Giardia spp. (3.2%), Cystoisospora spp. (5.6%), Sarcocystis spp. (0.2%), and Entamoeba spp. (2.4%). The presence of positive fecal samples in public areas and municipalities correlated with populations of up to 10,000 inhabitants (p = 0.023). Areas contaminated with feces were 63.4% more likely to contain parasites than other areas (odds ratio 1.6336). Favorable environmental factors combined with inadequate sanitary management contribute to a high risk of environmental contamination, representing a significant zoonotic potential and highlighting the need for improved public health policies and preventive measures.